add BLOCKING modifier to frameFlagTypes

src/graphics/EInkDynamicDisplay.cpp

@@ -458,15 +458,32 @@ void EInkDynamicDisplay::checkAsyncFullRefresh()
 // Figure out who runs the post-update code
 void EInkDynamicDisplay::endOrDetach()
 {
-    if (previousRefresh == FULL) {  // Note: previousRefresh is the refresh from this loop.
+    if (refresh == FULL) {
         asyncRefreshRunning = true; // Set the flag - picked up at start of determineMode(), next loop.
-        LOG_DEBUG("Async full-refresh begins\n");
+
+        if (frameFlags & BLOCKING)
+            awaitRefresh();
+        else
+            LOG_DEBUG("Async full-refresh begins\n");
     }
 
     // Fast Refresh
     else
         EInkDisplay::endUpdate(); // Still block while updating, but EInkDisplay needs us to call endUpdate() ourselves.
 }
+
+// Hold control while an async refresh runs
+void EInkDynamicDisplay::awaitRefresh()
+{
+    // Continually poll the BUSY pin
+    while (adafruitDisplay->epd2.isBusy())
+        yield();
+
+    // End the full-refresh process
+    adafruitDisplay->endAsyncFull(); // Run the end of nextPage() code
+    EInkDisplay::endUpdate();        // Run base-class code to finish off update (NOT our derived class override)
+    asyncRefreshRunning = false;     // Unset the flag
+}
 #endif // HAS_EINK_ASYNCFULL
 
 #endif // USE_EINK_DYNAMICDISPLAY

src/graphics/EInkDynamicDisplay.h

@@ -28,6 +28,7 @@ class EInkDynamicDisplay : public EInkDisplay
         RESPONSIVE = (1 << 1),  // For frames via forceDisplay()
         COSMETIC = (1 << 2),    // For splashes
         DEMAND_FAST = (1 << 3), // Special case only
+        BLOCKING = (1 << 4),    // Modifier - block while refresh runs
     };
     void addFrameFlag(frameFlagTypes flag);
 
@@ -112,6 +113,7 @@ class EInkDynamicDisplay : public EInkDisplay
 #if defined(HAS_EINK_ASYNCFULL)
     void checkAsyncFullRefresh(); // Check the status of "async full-refresh"; run the post-update code if the hardware is ready
     void endOrDetach();           // Run the post-update code, or delegate it off to checkAsyncFullRefresh()
+    void awaitRefresh();          // Hold control while an async refresh runs
     void endUpdate() override {}  // Disable base-class behavior of running post-update immediately after forceDisplay()
     bool asyncRefreshRunning = false; // Flag, checked by checkAsyncFullRefresh()
 #endif